1. Technical Field
The present invention relates to a virtual image display apparatus which presents a video image formed by an image display element and the like to a viewer, and particularly to a virtual image display apparatus which is preferably applied to a head mount display designed to be mounted on the head of the viewer.
2. Related Art
Various optical systems to be embedded in a virtual image display apparatus such as a head mount display (hereinafter, also referred to as an HMD) designed to be mounted on the head of a viewer have been proposed. For example, an optical system which uses a prism member configured of a relatively thick light guiding member arranged in front of the eyes and a light transmitting member joined to the tip end side of the light guiding member to display a virtual image and enable viewing of an external image has been known (see JP-A-2013-200553, for example).
According to the virtual image display apparatus which uses the prism member as described above, it is considered that a rib is provided in a periphery between a pair of facing main optical surfaces in the light guiding member and the like for convenience in aligning the optical surfaces or for a reason of a molding process. By providing such a rib, it is possible to easily align both the light guiding member and the light transmitting member during assembly for joining the light guiding member and the light transmitting member and to cause the rib to function as a guide for assembling the prism member, to which the light guiding member and the light transmitting member are joined, with another member. In addition, it is possible to facilitate separation of the light guiding member during injection molding or the like of the light guiding member by using the rib.
However, since the prism member configures an appearance of the virtual image display apparatus, there is a possibility that a necessity to hide or remove the aforementioned rib occurs. In addition, the shape including the rib brings about a complicated outer shape, and there is a possibility that design for the appearance is inevitably restricted.